I believe this was introduced in #12620. This may be expected behavior.

I came here to write about this too :)

I just merged a workaround for this: elm-tooling/elm-tooling-cli#128

In my case, this is the story (a bit of XKCD 1172 vibes here):

• Some people put -w "\n" in their .curlrc. Is it a good idea? I don’t know 🤷. But this StackOverflow answer has 600+ upvotes: https://stackoverflow.com/a/14614203/2010616
• That “elm-tooling” thing I linked to uses curl to download stuff. The checksums fail with that extra newline appended.
• I added -w "" as a workaround for people with -w "\n" in their .curlrc. Are there more things that people can set in .curlrc that will mess with my download script? Probably. Has anyone complained? None so far.
• I don’t want to use -q because if people configure proxy stuff in .curlrc I want that to be used.

Is it a bug? I’ll leave that to the maintainers to judge. Either way, here’s my workaround:

-w "%{stderr}"

%{stderr} doesn’t print anything of itself, it just makes the rest of the-w string get written to stderr. “The rest of the string” is nothing in this case. So in practice this has the same effect as the empty string, without being empty :)

@lydell thanks for the workaround!